(a) Field of the Invention
The present invention relates to a press apparatus, more particularly, to a press apparatus which may prevent wrinkles from forming on a flange surface of a panel.
(b) Description of the Related Art
Generally, a vehicle is manufactured by numerous assembling processes using about 20,000 to 30,000 parts.
In particular, a vehicle body is formed by a first assembling process such that vehicle body panels are produced in a press process, and each part of the vehicle body is then assembled in a vehicle body factory to form a vehicle body of a body-in-white (BIW) state.
In order to form the panels, as described above, a forming process is performed for press forming the panels in a predetermined shape with various presses, and then cutting, hole forming, curving, and bending are performed in press processes, such as trimming, piercing, flanging, and hemming.
In a press forming process, a flange of a panel is under processed considering elastic restoring. In particular, “Spring Back” occurs when a flat-rolled metal or alloy is cold-worked; upon release of the forming force, the material has a tendency to partially return to its original shape because of the elastic recovery of the material. This is called “Spring Back” and influenced not only by the tensile and yield strengths, but also by thickness, bend radius and bend angle.
Recently, to enhance the appearance of a vehicle, bent shapes are applied to a vehicle body. Particularly, for applying a panorama sunroof to the vehicle, forming depth may be required to be increased.
However, for applying deep forming depth to the vehicle body, two steps of forming processes, for example, a vertical direction flange forming process and a horizontal direction flange forming process, are required in the conventional art, and thus productivity may be deteriorated, and manufacturing cost may be increased.
Also, in cam forming process, tensile press forming may not be applied to the panel, and thus compress press forming may be applied. As a result, wrinkles may be formed on a flange surface contributing to an inferior appearance, and thus increasing an inferiority rate.
Due to such wrinkles, welding quality may be deteriorated, and elements may not be easily mounted to the vehicle body.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.